ICOS Science Conference 2020, Session 14

1. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Extreme productivity patterns during the spring bloom 2018 in the
Central Baltic Sea suggest vertical nutrient shuttling: Unforeseen
surprises for the fight against euthrophication in a warming world?
Gregor Rehder, Jens D. Müller, Henry Bittig, Mati Kahru,
Seppo Kaitala, Bernd Schneider, Simo-Matti Siiriä, Laura Tuomi, Norbert Wasmund
gregor-rehder@io-warnemuende.de

2. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Prologue
Prologue
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3. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Prologue
3

4. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
4
106CO2 + 16NO3
- + HPO4
2- + 122H2O + 18 H+
(CH2O)106(NH3)16(H3PO4) + 138O2∙
106CO2 + 16NO3
- + HPO4
2- + 122H2O + 18 H+
(CH2O)106(NH3)16(H3PO4) + 138O2∙
???CO2 + 16NO3
- + HPO4
2- + 122H2O + 18 H+
(CH2O)???(NH3)16(H3PO4) + ???+32O2∙
???CO2 + 16NO3
- + HPO4
2- + 122H2O + 18 H+
(CH2O)???(NH3)16(H3PO4) + ??? +32O2∙
Definition by Nixon (1995)
Prologue

5. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Prologue
Recognition of
variable C,N,P
ratios ....
... driven by
carbon
observations
From Schneider and Müller, 2018
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6. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Thespringtale(2018)
The Tale
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7. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Never (since 2003)
observed drop in pCO2 in
the Central Gotland
Basin in spring 2018
Thespringtale(2018)
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8. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
...translates to a fixation
of 250 mmol C / kg
• More than doubling
usual observations
Thespringtale(2018)
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9. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Meteorologicalforcing
Sunshine hour anomaly (March-Sept) (%)
Spatial distributions of the
monthly anomalies in solar
direct downwelling flux over the
Baltic Sea area from April to
July of 2018, in relation to the
1983-2017 monthly means
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10. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
SeaSurfaceTemperature
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11. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Upperwatercolumnindications
FMI Argo Float data – 2013-2018
SST MLD
Chl a O2sat
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12. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
SurfaceobservationsfromArgo
FMI Argo Float data, surface bin – 2013-201812

13. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Timingandextentofextremeprod.
(BY 20)
– Highest Chl a concentrations
mainly in first 10 days of
May
– Highest anomaly (relative to
10 days averages from the
1998 to 2018 climatology of
the ESA-CCL ocean color
data)
– Extending over a large part
of the central Baltic Sea
– Matches pCO2 drawdown
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14. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
SeparationofN-,P-,andC-uptake
• Uptake of N,P mostly (N) or completely (P) restricted to upper 20m until April 19th
• Depletion (N) and further strong uptake of (P) down to > 60m until May 13th, despite persistent
strong thermocline
• Inorganic carbon uptake restricted to upper 20 m
• In the surface layer, loss of 250 mmol/L C, but only 4.5 mmol/L nitrate and 0.6 mmol/L phosphate
• Requires active upward transport of nitrate and phosphate14

15. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Phytoplanktoncomposition
0
500
1000
1500
2000
2500
3000
3500
4000
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
Biomass[mgm-3]
Others
Prymnesiophyceae
Dinophyceae
Ciliophora
Bacillariophyceae
2018 spring
phytoplankton
• Dominance of
Dinoflagellates
• Almost exclusively
Peridiniella
catenata
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16. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Talesummary
• Extremely low pCO2 in late spring 2018
• Highest solar downward flux in May with
rapid surface warming
• Unpreceded biomass production in early May
in large areas of the central Baltic Sea
• Carbon fixation (net carbon productivity)
more than 3x that expected from N or P
winter concentrations
• Decoupling of vertical distribution of C,N,
and P
• Coincidences with strongest Dinoflagellate
bloom in observation record
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17. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Epilogue
Epilogue
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18. Rehder et al. ICOS Science Conference 2020
Extreme productivity patterns during the spring bloom 2018 in the Central Baltic Sea
Epilogue
Acknowledgement: THE BONUS
INTEGRAL project receives funding from
BONUS (Art 185), funded jointly by the
EU, the German Federal Ministry of
Education and Research, the Swedish
Research Council Formas, the Academy
of Finland, the Polish National Centre for
Research and Development, and the
Estonian Research Council.
• Derived from novel high resolution
monitoring technologies (VOS, Bio-
Argo, Remote sensing)
• Demonstrates need for carbon
observation network
• Timeliness of HELCOM EN CLIME,
also with focus on biogeochemical
functioning
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